1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor wafer having a high gate oxide film insulation (hereinafter referred as GOI: Gate Oxide film Insulation). In particular, it relates to a manufacturing process for semiconductor wafers, which can obtain a yield exceeding 60% when measuring the GOI and is performed by removing the factors that degrade the GOI produced in the manufacturing process of semiconductor wafers.
2. Description of the Prior Art
Conventionally, among the factors that degrade GOI, the factors that occur on the surfaces of semiconductor wafers during the manufacturing process from cutting of semiconductor ingots to mirror finish of the surface of semiconductor wafer, are removed by further processing. An example of this process is the sacrificial oxidation method. The method involves forming an oxidation film on the surface of semiconductor wafer by heat treatment, removing the oxidation film by etching and then washing.
However, in the heat treatment for forming the oxidation film, if there are metal contaminants, the metal contaminants diffuse into the inside of silicon crystals (hereinafter referred as contamination), and become defects of the silicon crystal per se.
Moreover, besides it takes time for the sacrificial oxidation treatment, the method is performed after the mirror processing, and thus once contamination exists, all the manufacturing steps before this step become void. Accordingly, the sacrificial oxidation method is not reliable and is inefficient.